Casters are commonly mounted to transport vehicles, such as carts, trailers, trucks, or dollies, and allow for rolling movement of the transport vehicle along a ground surface. Conventional casters generally include a horn (also referred to as a yoke) having a pair of legs that extend downwardly and support a caster wheel that rolls along the ground surface.
Casters may be designed to rotate, or “swivel,” about a vertical axis (termed “swivel” casters), or they may be fixed (termed “rigid” casters). Conventional swivel casters generally include a horn that is rotatably coupled to a swivel plate, which in turn is mounted to a vehicle, such that the horn and caster wheel may swivel about a vertical swivel axis relative to the swivel plate and the vehicle. This swiveling action enables the caster wheel to change direction while rolling, thereby allowing an operator to turn or otherwise steer the vehicle. In contrast, rigid casters generally include a horn that is rigidly attached to the vehicle via a mounting plate, such that the caster wheel does not swivel. Transport vehicles may be fitted with one or more swivel casters and one or more rigid casters, depending on the application and vehicle design. In a common arrangement, a vehicle may include swivel casters on a rear operator-end of the vehicle, and rigid casters on a front end of the vehicle. For improved vehicle maneuverability in tight spaces, the vehicle may be provided with swivel casters at both vehicle ends, as often seen on grocery carts, for example.
A transport vehicle with conventional casters may be used on rough or uneven surfaces. As such, the goods carried on the transport vehicle may be subject to damage because of the rough or uneven surfaces. Casters with a spring mechanism have been used on such transport vehicles to reduce the shock or possible damage to those goods carried on the transport vehicle over the rough or uneven surfaces. While absorbing shock due to the uneven surfaces, the transport vehicle may encounter depressions in the floor surface sufficiently deep to cause the spring loaded caster to lose contact with the surface. Should the caster over such a depression be a swivel caster, it will likely lose its alignment with the direction of travel. Keeping all mounted casters in contact with the floor, regardless of condition, may not be achievable with standard spring-loaded casters.
Accordingly, there remains a need for improvements to casters used on rough or uneven surfaces to address the shortcomings described above.